An apparatus for analyzing the output of a plurality of oil wells. The apparatus comprises: i) a plurality of test headers coupled to the plurality of wells via a field testing infrastructure; and ii) a test separator configured to select a first well for testing and to receive a multiphase fluid flow from a first one of the plurality of test headers, the first test header associated with the first well. The test separator is further configured to: iii) separate the multiphase fluid flow into a gas phase stream and a liquid phase stream; iv) measure a plurality of parameters of the gas phase stream and the liquid phase stream over a current period; v) for each of the plurality of parameters, determine a mean value, a standard deviation, a maximum value, and a minimum value in the current period; and vi) determine if a standard deviation associated with a first parameter exceeds a first threshold of a mean value associated with the first parameter. If the standard deviation exceeds the first threshold, the test separator flags the first oil well as having a problem.